LAUSR

Pyrenophora is not only as a genus of pathogens causing leaf damage but also as common seedborne fungi of Italian ryegrass (Lolium multiflorum Lam.). To elucidate the main seedborne Pyrenophora species, 36 seed samples of Italian ryegrass were collected; in total, 113 strains, representing 12.3% of all isolated strains (921), were identified as Pyrenophora species by the identity of ITS sequences in NCBI as well as the similarity of morphological characteristics, of which P. dictyoides (97) was the most frequent species. By pure culture technique, 24 representative pure isolates were eventually retained for further study. Based on DNA analysis of multiple loci (ITS, LSU, GPDH, CHS-1 and RPB1) and morphological characters, eight Pyrenophora species were finally identified, including P. avenicola, P. chaetomioides, P. dictyoides, P. lolii, P. nobleae, P. teres, P. triseptata and P. tritici-repentis; among them, P. avenicola, P. tritici-repentis and P. triseptata were newly reported on Italian ryegrass worldwide. Seed inoculation showed that P. dictyoides, P. lolii and P. teres remarkably decreased the final germination percentages (FGP) and germination indexes (GI) compared with control treatments (P ≤ 0.05); and plant inoculation showed that P. dictyoides, P. lolii and P. nobleae could cause typical brown spot in vivo with higher infection rate (P ≤ 0.05). In conclusion, pathogenicity tests showed that all Pyrenophora species could both inhibit seed germination and infect Italian ryegrass plant to different degrees; among them, P. dictyoides was the most important seedborne pathogen coupled with the isolation and infection rate, followed by P. lolii and P. nobleae. The data generated in this study are helpful for the accurate identification of Pyrenophora species, and the development of seedborne disease management strategies.